Overhead electric power distribution lines require circuit disconnect means at certain locations; and since such distribution lines commonly operate in a three-phase system, there are three associated lines which ordinarily must be disconnected and reconnected simultaneously. This requires group operated switches, and for safety and convenience during servicing of the lines, it is desirable that a person be able to open and close the circuit disconnect means on the overhead lines from ground level.
Bridges U.S. Pat. No. 3,637,959 discloses a prior art mechanism for group operation of three switches on parallel overhead electric lines. The disconnect switches of U.S. Pat. No. 3,637,959 are mounted in the electric lines; but as indicated in that patent it is also well known to mount such disconnect switches on a cross arm or on a pole top frame.
Prior art group operated circuit disconnect devices have various disadvantages which are eliminated in the apparatus of the present invention. In the first place, the prior art apparatus usually has rotatable or sliding parts which are exposed to the weather where they may become corroded, or where they may become immobilized in the winter because of ice formed on them.
In addition, some commercially available group operated disconnect switches require substantial field adjustment at the time of installation; and this, of course, is to be avoided to the greatest possible extent.